root/fs/udf/lowlevel.c

DEFINITIONS

1. udf_get_last_session
2. udf_get_last_block

   1 /*
   2  * lowlevel.c
   3  *
   4  * PURPOSE
   5  *  Low Level Device Routines for the UDF filesystem
   6  *
   7  * COPYRIGHT
   8  *      This file is distributed under the terms of the GNU General Public
   9  *      License (GPL). Copies of the GPL can be obtained from:
  10  *              ftp://prep.ai.mit.edu/pub/gnu/GPL
  11  *      Each contributing author retains all rights to their own work.
  12  *
  13  *  (C) 1999-2001 Ben Fennema
  14  *
  15  * HISTORY
  16  *
  17  *  03/26/99 blf  Created.
  18  */
  19 
  20 #include "udfdecl.h"
  21 
  22 #include <linux/blkdev.h>
  23 #include <linux/cdrom.h>
  24 #include <linux/uaccess.h>
  25 
  26 #include "udf_sb.h"
  27 
  28 unsigned int udf_get_last_session(struct super_block *sb)
  29 {
  30         struct cdrom_multisession ms_info;
  31         unsigned int vol_desc_start;
  32         struct block_device *bdev = sb->s_bdev;
  33         int i;
  34 
  35         vol_desc_start = 0;
  36         ms_info.addr_format = CDROM_LBA;
  37         i = ioctl_by_bdev(bdev, CDROMMULTISESSION, (unsigned long)&ms_info);
  38 
  39         if (i == 0) {
  40                 udf_debug("XA disk: %s, vol_desc_start=%d\n",
  41                           ms_info.xa_flag ? "yes" : "no", ms_info.addr.lba);
  42                 if (ms_info.xa_flag) /* necessary for a valid ms_info.addr */
  43                         vol_desc_start = ms_info.addr.lba;
  44         } else {
  45                 udf_debug("CDROMMULTISESSION not supported: rc=%d\n", i);
  46         }
  47         return vol_desc_start;
  48 }
  49 
  50 unsigned long udf_get_last_block(struct super_block *sb)
  51 {
  52         struct block_device *bdev = sb->s_bdev;
  53         unsigned long lblock = 0;
  54 
  55         /*
  56          * ioctl failed or returned obviously bogus value?
  57          * Try using the device size...
  58          */
  59         if (ioctl_by_bdev(bdev, CDROM_LAST_WRITTEN, (unsigned long) &lblock) ||
  60             lblock == 0)
  61                 lblock = i_size_read(bdev->bd_inode) >> sb->s_blocksize_bits;
  62 
  63         if (lblock)
  64                 return lblock - 1;
  65         else
  66                 return 0;
  67 }